63 research outputs found
Coherent Resonant Coupling between Atoms and a Mechanical Oscillator Mediated by Cavity-Vacuum Fluctuations
We show that an atom can be coupled to a mechanical oscillator via quantum
vacuum fluctuations of a cavity field enabling energy transfer processes
between them. In a hybrid quantum system consisting of a cavity resonator with
a movable mirror and an atom, these processes are dominated by two
pair-creation mechanisms: the counter-rotating (atom-cavity system) and
dynamical Casimir interaction terms (optomechanical system). Because of these
two pair-creation mechanisms, the resonant atom-mirror coupling is the result
of high-order virtual processes with different transition paths well described
in our theoretical framework. We perform a unitary transformation to the
atom-mirror system Hamiltonian, exhibiting two kinds of multiple-order
transitions of the pair creation. By tuning the frequency of the atom, we show
that photon frequency conversion can be realized within a cavity of multiple
modes. Furthermore, when involving two atoms coupled with the same mechanical
mode, a single vibrating excitation of the mechanical oscillator can be
simultaneously absorbed by the two atoms. Considering recent advances in strong
and ultrastrong coupling for cavity optomechanics and other systems, we believe
our proposals can be implemented using available technology.Comment: 18 pages, 13 figur
Activation of indistinguishability-based quantum coherence for enhanced metrological applications with particle statistics imprint
Quantum coherence, an essential feature of quantum mechanics allowing quantum superposition of states, is a resource for quantum information processing. Coherence emerges in a fundamentally different way for nonidentical and identical particles. For the latter, a unique contribution exists linked to indistinguishability that cannot occur for nonidentical particles. Here, we experimentally demonstrate this additional contribution to quantum coherence with an optical setup, showing that its amount directly depends on the degree of indistinguishability, and exploiting it in a quantum phase discrimination protocol. Furthermore, the designed setup allows for simulating fermionic particles with photons, thus assessing the role of exchange statistics in coherence generation and utilization. Our experiment proves that independent indistinguishable particles can offer a controllable resource of coherence and entanglement for quantum-enhanced metrology
The politics of heroes through the prism of popular heroism
This is the author accepted manuscript. The final version is available from Palgrave Macmillan via the DOI in this record.In modern day Britain, the discourse of national heroification is routinely utilised by politicians, educationalists and cultural industry professionals, whilst also being a popular concept to describe deserving ‘do-gooders’ who contribute to British society in a myriad of ways. We argue that although this heroification discourse is enacted as a discursive device of encouraging politically and morally desirable behaviour, it is dissociated from the largely under-explored facets of contemporary popular heroism. To compensate for this gap, this paper explores public preferences for heroes using survey data representative of British adults. This analysis demonstrates a conceptual stretching in the understanding of heroism, and allows identifying age- and gender-linked dynamics which effect public choices of heroes. In particular, we demonstrate that age above all determines the preference for having a hero, but does not explain preferences for specific hero-types. The focus on gender illustrates that the landscape of popular heroism reproduces a male-dominated bias which exists in the wider political and cultural heroification discourse. Simultaneously, our study shows that if national heroification discourse in Britain remains male-centric, the landscape of popular heroism is characterised by a gendered trend towards privatisation of heroes being particularly prominent amongst women. In the conclusion, this paper argues for a conceptual revision and re-gendering of the national heroification discourse as a step towards both empirically grounded, and age- and gender-sensitive politics of heroes and heroines.AHR
A CRISPR screen identifies a pathway required for paraquat-induced cell death
Paraquat, a herbicide linked to Parkinson's disease, generates reactive oxygen species (ROS), which causes cell death. Because the source of paraquat-induced ROS production remains unknown, we conducted a CRISPR-based positive-selection screen to identify metabolic genes essential for paraquat-induced cell death. Our screen uncovered three genes, POR (cytochrome P450 oxidoreductase), ATP7A (copper transporter), and SLC45A4 (sucrose transporter), required for paraquat-induced cell death. Furthermore, our results revealed POR as the source of paraquat-induced ROS production. Thus, our study highlights the use of functional genomic screens for uncovering redox biology
Gene Expression Profiling in Gastric Mucosa from Helicobacter pylori-Infected and Uninfected Patients Undergoing Chronic Superficial Gastritis
Helicobacter pylori infection reprograms host gene expression and influences various cellular processes, which have been investigated by cDNA microarray using in vitro culture cells and in vivo gastric biopsies from patients of the Chronic Abdominal Complaint. To further explore the effects of H. pylori infection on host gene expression, we have collected the gastric antral mucosa samples from 6 untreated patients with gastroscopic and pathologic confirmation of chronic superficial gastritis. Among them three patients were infected by H. pylori and the other three patients were not. These samples were analyzed by a microarray chip which contains 14,112 cloned cDNAs, and microarray data were analyzed via BRB ArrayTools software and Ingenuity Pathways Analysis (IPA) website. The results showed 34 genes of 38 differentially expressed genes regulated by H. pylori infection had been annotated. The annotated genes were involved in protein metabolism, inflammatory and immunological reaction, signal transduction, gene transcription, trace element metabolism, and so on. The 82% of these genes (28/34) were categorized in three molecular interaction networks involved in gene expression, cancer progress, antigen presentation and inflammatory response. The expression data of the array hybridization was confirmed by quantitative real-time PCR assays. Taken together, these data indicated that H. pylori infection could alter cellular gene expression processes, escape host defense mechanism, increase inflammatory and immune responses, activate NF-κB and Wnt/β-catenin signaling pathway, disturb metal ion homeostasis, and induce carcinogenesis. All of these might help to explain H. pylori pathogenic mechanism and the gastroduodenal pathogenesis induced by H. pylori infection
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